BEIJING, April 10 (Xinhua) -- A new study led by Chinese scientists, published Friday in the journal Science, has uncovered the hidden forces behind the creation of North America's Yellowstone supervolcano.
Researchers from the Institute of Geology and Geophysics (IGG) at the Chinese Academy of Sciences and the University of Illinois used high-precision computer models to reveal, for the first time, how the magma system beneath Yellowstone formed.
Yellowstone is one of the most famous supervolcanoes on Earth. Over the past 2.1 million years, it has erupted twice on a super scale -- once 2.08 million years ago and again 630,000 years ago. Each eruption blasted out between 2,500 and 1,000 cubic kilometers of solid material. Such massive eruptions can significantly impact the global climate and affect human society.
For years, scientists thought Yellowstone was fed by a vertical plume of hot rock rising from deep within Earth, like a giant chimney. But new observations showed a different picture. The magma system beneath Yellowstone is not vertical. Instead, it tilts to the southwest as it goes deeper, forming a slanted shape.
Using advanced data and models of North America's deep interior, the researchers discovered that a leftover piece of an ancient tectonic plate -- called the Farallon slab -- is sinking deep beneath the eastern United States. As it sinks, the slab pulls hot material from the asthenosphere (a soft, slow-flowing layer beneath Earth's rigid outer shell) below as far as the west coast toward it. The result is a fast, eastward drift of hot rock beneath western North America.
As this eastward "mantle wind" flows beneath Yellowstone, it squeezes through a narrow passage in the continent's rigid outer layer, called the lithosphere. The stretching between the buoyant rising hot mantle and the east-flowing mantle flow causes the asthenosphere to melt, producing large amounts of magma. At the same time, the eastward pressure from the mantle wind and westward pull from the shallow crust create strong tension inside the lithosphere beneath Yellowstone. This tension literally tears the lithosphere open, forming a tilted, chimney-like channel. Magma then rises and moves along this channel, like climbing stairs.
"The model's predictions match real-world observations from geophysical imaging, rock chemistry and gravity measurements," said Liu Lijun, the corresponding author.
"Importantly, the study rules out the traditional vertical plume model," said Cao Zebin, a researcher at the IGG.
According to the scientists, this new understanding may apply to other volcanoes around the world, including the Jingpohu volcano in northeastern China, the Toba supervolcano in Southeast Asia, the Kamchatka volcanoes in Russia, and the Altiplano-Puna volcano in South America.
The study offers a fresh way to understand how volcanoes work and could help improve eruption forecasts and disaster prevention in the future, Cao added. ■
